stetson



(No Model.) 2 SheetsSheet 1. G. R. STBTSON.

MACHINE FOR MAKING TWIST DRILLS.

No. 312,401. Patented Feb. 17, 1 885.

INVENTUR (No Model.) 2.Sheets-Sheet 2.

G. R. STETSON.

MACHINE FOR MAKING TWIST DRILLS.

Patented Feb. 17, 1885.

WITNESEEE INVENTEJR M r fifw y N. PLTERS. PholmLJlhngrnphcr. Washi nnnnnn c UNrrn TATES aren't rrrcn.

GEORGE RIPLEY STETSON, OF NEXV BEDFORD, MASSACHUSETTS, ASSIGNOR TOHIMSELF AND THE MORSE TWIST DRILL AND MACHINE COMPANY,

OF SAME PLACE.

IVlACl-HNE FOR MAKING TWlST-DRILLS.

SPECIFICATION forming part of Letters Patent No. 312,401, dated February17, 1885.

Application filed October :25, 1883. (No model.)

To (all whom it may concern:

Be it known that I, GEORGE E. SrnrsoN, of New Bedford, in the county ofBristol and State of Massachusetts, have invented certain new and usefulImprovementsin Machines for Making Twist-Drills, of which the followingis the specification. I

My invention relates to the class of machines illustrated in LettersPatent No. 178, 250,

and to improvements in such machines.

In my improved machine the gradually-expedited advance of the mandreland blank, in order to obtain the increasing pitch or inclination of thegroove, is secured by the action of a suitably-formed cam impingingdirectly upon the mandrel itself, instead of, as in the patent referredto, upon radial rollerstuds or other equivalent interposed devicesbetween the face of the cam and that part of the mandrel against whichits action is brought to bear.

The drawings illustrate a machine of this construction, Figure 1 beingan elevation,and Fig. 2 a section, in which a wedge-cam is employed, andFig.3 being a plan view of the cam and its operating-pinion. Figs. 4 and5 are views in elevation and section, showing an eccentric in place ofthe wedge-cam.

The operating mechanism in all the draw ing is substantially like thatshown in the granted patent above referred to. The wedgecam may beconveniently constructed in the form of a parallelogram interiorlyslotted, and provided upon one exterior side with a 5 rack, a, Fig. 3,by which motion is given to it when such a form of cam is used. I preferto form the mandrel B at that portion of it exposed to the cam actionwith an annular boss having a partly-spherical contour,

which bears against the cam.

Instead of the sliding cam, I may use a rotating cam, O, with suitableoperating-gearing, 0 c, as shown in Figs. 4 and 5. As the cam is caused,by means of the gears c c or 5 the pinion b and rack a, to act againstthe mandrel B, the graduated cam-face advances the mandrel which carriesthe drill D in direct proportion to the pitch of the cam,which,

in turn, is made tocorrespond to the required increased pitch in thedrill, and the advance of the madrel being thus increased in speed asthe cutting progress, there is a corresponding increase in the pitch ofthe drill, which increase in pitch it is the object of this machine toobtain.

For the'more convenient return of the man drel at the end of the cuttingoperation, I pro vide it with an extension, E, bearing against andcompressing a spring, 6', as the mandrel advances, which compressedspring, as will be seen, acts to bring the mandrel back after itsforward motion has ended.

The other parts of the machine present no substantial difference fromthose shown in the Letters Patent above referred to. The mandrel isguided in its forward and back motions by its bearings in the gears,which are -splined to it to permit of its passage through them.

From the foregoing it will be perceived that the structure ororganization of my improved twist-drill machine is materiallysimplified; that I dispense not only with the frictionrollers shown inthe said patent, but also with the disk provided for carrying thefrictionrollers, and transfer the cam action directly to themandrel,instead of having it communicated indirectly through expensiveintermediate appliances. The friction-rollers and the disk in such amachine as the patented one referred to have in practice to be madestrong in order to resist the strains applied, and they are consequentlyexpensive. They are also liable to get out of order,and constitute anunnecessary element to the practical efficiency of the machine. Besidesthis, itis necessary to have more than one bearing upon the cam, wheresuch disk and friction-rollers are employed, as illustrated in saidpatent, in order to give the proper direction of force of the 0 camaction. This results in the necessity of having what is really a triplecam,equivalent practically to three wedges; otherwise a proper balanceof force could not be obtained.

It will be seen that in order to accommodate the change andsimplification above set forthI have very greatly modified theconstruction as well as the relations of the cam applied to the mandrel,and that the result is a materially cheaper, simpler, more efficient,and 5 every way superior machine.

I claim- In a machine for making increased twist-- drills, thecombination of a mandrel toadvance and rotate the drill-blank, and asuit- 10 ably-formed cam acting directly against the mandrel, wherebythe advance of the latter is accelerated as the cutting progresses toincrease the pitch of the drill. 4

In testimony whereof I have hereunto subscribed my name this 18th day ofOctober, A. 15 D. 1883.

GEORGE RIPLEY STETSON. \Vitnesses:

'I. M. STETSON, HENRY B. WORTH.

